This may or may not be R2-B1 because the original R2-B1 was blown off the wing of Queen Amidala’s starship was attacked by the Trade Federation while escaping from Naboo. There are a lot of R2 units we only get to know the ones with short names like R2-B1 and R2-D2. Just realized that R2-B1 had front leg so this may not be an R2 unit at all.